Quantification of platelets and platelet derived growth factors from platelet-rich-plasma (PRP) prepared at different centrifugal force (g) and time

Does the Uterine Ozone Therapy Alter the Transcript Profile of Anti- and Proinflammatory Genes in Mares With Endometritis?

This study aimed to evaluate the localised effects of intrauterine ozone therapy on endometrial recovery in mares with endometritis. Our investigation assessed changes in gene expression profiles of anti-inflammatory (IL-1RA and IL-10), proinflammatory (IL-R1B3i and TNFα) and pleiotropic (IL-6) cytokines, along with detailed histological measurements of epithelial and endometrial thickness and the glandular area ratio. Twenty mares were assigned to a 2 × 2 factorial design based on endometritis diagnosis and treatment (control or 42 μg/mL ozone insufflation), resulting in four groups: NC (negative for endometritis/control), NO (negative/ozone), PC (positive/control) and PO (positive/ozone). Oestrus was induced with 2 mg of oestradiol benzoate on Days -1, 1 and 3, plus 1 mg on Day 5. Day 0 marked the initial uterine treatment, followed by insufflations on Days 1 and 2 with O3 (ozone) or O2 (control). Uterine biopsies were taken before treatment on Day 0 and Day 6 for histological analysis and gene expression assessment. Data were analysed using a statistical model that included endometritis status, treatment type, biopsy times (D0 and D6) and their interactions, analysed with Proc Glimmix. Regardless of treatment or endometritis status, significant biopsy effects (p < 0.01) indicated increased epithelial height and endometrial thickness in Day 6 samples. Analysis of IL-1 and TNFα revealed a significant interaction (p < 0.05) among endometritis, treatment and biopsy, with higher IL-1B3i expression on Day 6 in the PC group. The treatment effect (p < 0.04) showed a higher frequency (p < 0.01) of animals with positive modulation in the PC group (66.7%) versus the PO group (0.0%). An interaction effect (p = 0.08) between endometritis and treatment resulted from higher IL-1RA expression on Day 6 in the PC group compared to the PO group. Biopsy effect was significant for IL-10 (p < 0.01), indicating higher values in the second sample associated with tissue repair. In the short-term evaluation, ozone therapy did not influence endometrial morphology and may modulate cytokine expression, specifically the reduction in IL-1 and TNFα levels. Therefore, this therapy appears to be a safe and potentially effective treatment for modulating the inflammatory response in mares with endometritis.

The Efficacy of Local Autologous Platelet-Rich Plasma Prepared by Single and Double Spin Methods in the Treatment of Chronic Ulcer

BACKGROUND

Chronic nonhealing ulcers present significant challenges in diabetic, dermatological, and surgical patients. Platelet-rich plasma (PRP), enriched with bioactive factors, offers promise for wound healing enhancement. This study evaluates PRP's efficacy, prepared via single and double spin methods in nonhealing chronic ulcers.

METHODS

 Twenty-two patients aged 18-65 years participated and 100 mL of blood was drawn into citrate phosphate dextrose adenine (CPDA) bags with all aseptic precautions. PRP was prepared by single and double spin methods. Patient serum and 10% calcium gluconate were added to fibrin gel. PRP was injected around the ulcer and then dressed. Dressings were changed on the fifth, 15th, and 20th days with PRP. Evaluation occurred on day 30 using surface area and volume assessments by both methods.

RESULTS

The single spin PRP group and double spin PRP group had 11 patients each with hemoglobin range of 10.79±1.88 to 12.63±2.22 g/dL. Initial lesions (16.27 cm²) significantly reduced to 14.76 cm² after double spin PRP sessions (p=0.005) and Initial lesions (9.87 cm²) significantly reduced to 7.65 cm² after single spin PRP sessions (p=0.005). Platelet count differences between whole blood and PRP were significant (p<0.05).

CONCLUSIONS

The single spin PRP method exhibited considerable improvements in healing parameters, showcasing its potential for chronic ulcer management.

Optimizing Platelet-Rich Plasma: Spin Time and Sample Source

The buff-colored layer separating the plasma from red blood cells (RBCs) in centrifuged blood was named the "buffy coat" in the late 19th century. The division of platelets (PLTs) and leukocytes (WBCs) between the buffy coat, plasma, and RBC layers in centrifuged blood has not been described before. In this study, we centrifuged 8.5 mL anticoagulated blood samples at 1000× g for 1, 2, 3, 5, 10, and 20 min. We then divided each sample into ten layers and analyzed each layer for cellular composition and mean platelet volume (MPV). Our results show that even after 20 min of centrifugation, about 15% of platelets remain in the plasma layers and 65% in the RBC layers. We found that the platelet count achieved from aspiration of 1 mL volume was optimal, with aspiration beginning 1/2 mL below the buffy coat and extending 1/2 mL above the buffy coat rather than beginning at the buffy coat itself and aspirating only plasma. Using this method of aspiration, we found that the total platelet count means reached a maximum in the 1 mL around the buffy coat after only 5 min of centrifugation.

Role of platelet-rich plasma in the treatment of rotator cuff tendinopathy

Shoulder pain is a common musculoskeletal complaint, and rotator cuff (RC) pathologies are one of the main causes. The RC undergoes various tendinopathic and avascular changes during the aging process. Other degenerative changes affecting its healing potential make it an appealing target for biological agents. Platelet-rich plasma (PRP) has demonstrated the potential to deliver a high concentration of several growth factors and anti-inflammatory mediators, and its clinical use is mainly supported by experiments that demonstrated its positive effect on muscle, ligaments, and tendinous cells. This review aimed to specify the role of PRP and its future applications in RC tendinopathies based on the current clinical evidence. Due to the different characteristics and conflicting outcomes, clinicians should use PRP with moderate expectations until more consistent evidence is available. However, it is reasonable to consider PRP in patients with contraindications to corticosteroid injections or those with risk factors for inadequate healing. Its autologous origin makes it a safe treatment, and its characteristics make it a promising option for treating RC tendinopathy, but the efficacy has yet to be established.

Quality Analysis of Autologous Platelet-Rich Plasmapheresis

To summarized the technology of autologous platelet-rich plasmapheresis and analyzed the product quality, in order to provide safe and effective product guarantee service for clinical treatment. Technical parameters were set according to patient age, weight, height, and preoperative routine blood indices. Autologous platelet-rich plasma (PRP) was collected, and the product quality and adverse reactions of patients were statistically analyzed. Autologous PRP had platelet (PLT), white blood cell (WBC), and red blood cell (RBC) counts of (1250.26 ± 435.88) × 109/L, (1.19 ± 1.95) × 109/L, and (0.05 ± 0.04) × 1012/L, respectively. The PLT enrichment ratio in PRP was 5.66 ± 1.66. There was no significant difference in PLT, RBC, WBC, or hematocrit before and after apheresis (P > 0.05). The incidence of adverse reactions was 8%, and all were mild. When clinical patients use PRP in the treatment of diseases, autologous platelet-rich plasmapheresis technology was used to apheresis PRP, which has good product quality and few adverse reactions, and thus can be adopted more widely.

Standardization and validation of a conventional high yield platelet-rich plasma preparation protocol

BACKGROUND

Of late, numerous randomised controlled trials report platelet-rich plasma (PRP) to be ineffective with preparation protocols of low platelet yield despite using expensive commercial PRP kits.

OBJECTIVE

This study aims to identify and standardize a preparation protocol for PRP with maximum platelets yield and concentration to obtain favourable results without the use of commercial preparation kits.

MATERIALS & METHODS

Blood samples were collected from 40 healthy volunteers who signed informed consent for participation in the study. The double spin protocol of PRP preparation was analyzed for variables such as centrifugal acceleration, time, and volume of blood processed and final product utilized. The final PRP prepared was investigated for platelet recovery, concentration, integrity, and viability. Each protocol investigated with technical and biological duplicates to avoid reporting and sampling bias.

RESULTS

We noted maximum platelet recovery (86-99%) with a consistent 6.4 ± 0.8 times the baseline concentration of platelets with first centrifugation at 100g for 15 min followed by second centrifugation at 1600g for 20 min. We did not note a loss of integrity or viability of the platelets in the final product from the above-said protocol. We also validated the protocol among all the study participants demonstrating consistency.

CONCLUSION

The preparation of PRP by the double-spin protocol using 10 ml of blood at 100 g followed by 1600 g for 15 and 20 min respectively in a 15 ml tube and using the lower 1/3rd of the final product demonstrated consistent high platelet recovery (86-99%) and concentration (6x) without disturbing the platelet integrity or viability.

Comparing the immunomodulatory properties of equine BM-MSCs culture expanded in autologous platelet lysate, pooled platelet lysate, equine serum and fetal bovine serum supplemented culture media

Joint injury often leads to cartilage damage and posttraumatic inflammation, which drives continued extracellular matrix degradation culminating in osteoarthritis. Mesenchymal stem cells (MSCs) have been proposed as a biotherapeutic to modulate inflammation within the joint. However, concerns have been raised regarding the immunogenicity of MSCs cultured in traditional fetal bovine serum (FBS) containing media, and the potential of xenogenic antigens to activate the immune system causing rejection and destruction of the MSCs. Xenogen-free alternatives to FBS have been proposed to decrease MSC immunogenicity, including platelet lysate (PL) and equine serum. The objective of this study was to compare the immunomodulatory properties of BM-MSCs culture-expanded in media supplemented with autologous PL (APL), pooled PL (PPL), equine serum (ES) or FBS. We hypothesized that BM-MSCs culture expanded in media with xenogen-free supplements would exhibit superior immunomodulatory properties to those cultured in FBS containing media. Bone marrow-derived MSCs (BM-MSCs) were isolated from six horses and culture expanded in each media type. Blood was collected from each horse to isolate platelet lysate. The immunomodulatory function of the BM-MSCs was assessed via a T cell proliferation assay and through multiplex immunoassay quantification of cytokines, including IL-1β, IL-6, IL-8, IL-10, and TNFα, following preconditioning of BM-MSCs with IL-1β. The concentration of platelet-derived growth factor BB (PDGF-BB), IL-10, and transforming growth factor-β (TGF-β) in each media was measured via immunoassay. BM-MSCs cultured in ES resulted in significant suppression of T cell proliferation (p = 0.02). Cell culture supernatant from preconditioned BM-MSCs cultured in ES had significantly higher levels of IL-6. PDGF-BB was significantly higher in APL media compared to FBS media (p = 0.016), while IL-10 was significantly higher in PPL media than ES and FBS (p = 0.04). TGF-β was highest in APL media, with a significant difference in comparison to ES media (p = 0.03). In conclusion, expansion of equine BM-MSCs in ES may enhance their immunomodulatory abilities, while PL containing media may have some inherent therapeutic potential associated with higher concentrations of growth factors. Further studies are needed to elucidate which xenogen-free supplement optimizes BM-MSC performance.

Effect of platelet-rich plasma injection combined with individualised comprehensive physical therapy on temporomandibular joint osteoarthritis: A prospective cohort study

BACKGROUND

The effectiveness of platelet-rich plasma (PRP) injection combined with physical therapy for the treatment of temporomandibular joint osteoarthritis (TMJ-OA) has not been studied.

OBJECTIVES

To assess the effectiveness of PRP injection combined with individualised comprehensive physical therapy for the treatment of TMJ-OA.

METHODS

This prospective cohort study included 40 patients with TMJ-OA who received PRP injection or PRP injection combined with individualised comprehensive physical therapy. Pain intensity, maximum mouth opening, temporomandibular joint sounds, and the Jaw Functional Limitation Scale (JFLS) scores and imaging findings were compared before treatment and during follow-up.

RESULTS

The pain intensity, maximum mouth opening, and temporomandibular joint sounds of the two groups significantly improved with an increase in treatment time (p < .05). The pain improvement in the combined treatment group was greater than that in the PRP injection group at 3 and 6 months (p < .05). The improvement of mouth opening was better in the combined treatment group, whereas the improvement of joint sounds was better in the PRP injection group. The improvement in JFLS scores in the combined treatment group was greater than that in the PRP injection group at 6 months (p < .05). The imaging improvement rates of the two groups were similar.

CONCLUSIONS

Platelet-rich plasma injection can significantly improve pain, mouth opening, abnormal joint sound, and mandibular function in patients with TMJ-OA and has good repair effect on condylar bone defects. PRP injection combined with individualised comprehensive physical therapy can effectively control the medium- and long-term pain of patients.

Editorial Commentary: Platelet-Rich Plasma Shows Promise for Improving Shoulder Tendinopathy

Platelet-rich plasma (PRP) injections continue to be used at increasing rates to treat common musculoskeletal conditions. PRP has a low-risk profile and emerging in vitro evidence to support its positive effects on soft-tissue healing. PRP has been shown to be of benefit for knee osteoarthritis, but less has been published regarding the shoulder. PRP delivers a high concentration of growth factors, cytokines, and other important inflammatory modulators. Its use is appealing for treating partial-thickness rotator cuff tears, subacromial bursitis, and rotator cuff tendinopathy since rotator cuff tendons often have poor healing capacity due to intrinsic degeneration. PRP has been shown to increase cell proliferation and matrix synthesis in tenocytes, which may aid tendon regeneration and healing. Adult tendons also contain a small amount of tendon progenitor cells, which can be induced to an active state by PRP. In addition, PRP is an autologous biologic agent and easy to acquire and administer in an outpatient clinical setting. Clinical studies continue to lag and are often heterogenous in quality and in results. PRP can vary widely based on multiple intrinsic and extrinsic factors, including patient age, sex, activity level, centrifugation speed, and number of centrifugation cycles. Thus, quality research methods should include reporting using the PAW (platelets/activation/white blood cells) system. Clinicians should remain cautiously optimistic about the future role of PRP injections in the shoulder.

PRP does not improve the objective outcomes of anterior cruciate ligament reconstruction: a systematic review and meta-analysis

PURPOSE

Platelet rich plasma (PRP) has been used in association with anterior cruciate ligament resconstruction (ACLR) to improve rehabilitation. The purpose was to systematically review the literature to compare the effects of PRP on ACLR in its objective and subjective outcomes.

METHODS

A systematic review of the MEDLINE, Web of Science, Embase, Scopus, and Cochrane databases was performed. Two independent reviewers included all the English language literature of patients undergoing primary ACLR with autograft combined with PRP. The outcomes analyzed were graft ligamentization (MRI), tibial and femoral tunnel widening (MRI), knee laxity, IKDC, Lysholm, Tegner activity scale and visual analog scale.

RESULTS

Nine studies were included with a total of 525 patients. PRP did not improve ligamentization of graft (standardized mean difference (SMD): 0.01 [95% CI: - 0.37; 0.39]), did not lead to lesser tunnel widening (SMD: 0.71 [95% CI: - 0.12; 1.54]), or lead to lesser knee laxity (raw mean difference: 0.33 [95% CI: - 0.84; 0.19]). Although there was statistical significance for PRP effects on Lysholm score and VAS (p < 0.01), their magnitude was limited.

CONCLUSION

PRP showed no improvement in objective outcomes like ligamentization and less tunnel widening, while it showed just small improvements in terms of Lysholm, VAS and knee laxity. Therefore, there is not enough evidence to support a recommendation in favor of PRP and more research is needed.

LEVEL OF EVIDENCE

I.

What Is the Adequate PRP Dose for an Effective Treatment? An In Vitro Experimental Study on the Skin

BACKGROUND

The clinical results of many studies on platelet-rich plasma (PRP) differ due to a lack of standardization in PRP preparation and administration as well as many variables such as PRP preparation methods, platelet concentration, and platelet activation.

OBJECTIVES

The authors sought to investigate a different variable that will affect PRP application results. How much PRP should be injected into the unit area of tissue for an effective PRP treatment?

METHODS

The study was performed on fresh surplus tissues of 20 patients that were discarded in abdominoplasty and mammoplasty operations. Nine areas of 4 cm2 were marked on the skin. Fluorescein-stained PRP was injected intradermally with 3 different gauge needles at 3 different doses (0.01, 0.03, and 0.05 mL). After injections, spreads of the fluorescent dye-covered areas in horizontal and vertical planes were measured and compared. For the horizontal plane measurements, the dye spread was measured first from the surface of the skin and second from the dermal surface of the skin. In addition, the width and depth of the dye spread in the dermis were measured from vertical sections.

RESULTS

Changing the needle diameter does not affect the width or depth (thickness) of the PRP spread in the dermis. Increasing the applied dose to 0.03 mL increases the spread to the width and depth (thickness).

CONCLUSIONS

In research evaluating the effectiveness of PRP treatments, it is necessary to report the volume of PRP to be applied per unit of tissue.

The measurement of wound tensile strength and the effect of PRP on wound tensile force: an experimental investigation on rabbits

Platelets in PRP are used for their functions in the initiation and regulation of the wound healing process and are used for the repair of injured tissues and the rejuvenation of healthy tissues. In this study, we evaluated the effect of a single dose platelet-rich plasma on skin wound healing and we demonstrated the effect of platelet-rich plasma on skin wound healing by measuring changes in the wound tensile strength.Material and methods: A total of 8 incisions, each 3 cm long, were made on the back skin on both sides of the vertebral column of 12 rabbits. After suturing their backs with staples, platelet rich plasma (PRP) was injected into the edges of the wounds on the left side and saline solution (saline) was injected into the edges of the wounds on the right side. The tensile force that causes wounds to rupture by applying tension was measured on the 7th, 14th, 21st, and 28th days with the help of a special home-designed device.Results: The mean PRP enrichment was 3.19 fold over peripheral blood. The saline to PRP tensile strength ratios on the 7th, 14th, 21st, and 28th days were calculated as 75.7%, 104.0%, 105.3% and 86.5%, respectively. Overall, the difference in the tensile strength for wounds that had received saline or PRP was in-significant.Conclusion: The application of PRP increases the tensile strength of the wound in the early period. It is possible to measure the tensile strength precisely in in vivo studies with economical home-designed devices.

Does the use of Dermojet affect the concentration of platelet-rich plasma? An in vitro experimental investigation

Needle-free injection systems with high jet pressure have been used for seven decades for drug or vaccine administration via intradermal, subcutaneous, and intramuscular routes. These systems are used for the application of mesotherapy drugs in plastic surgery and dermatology. Platelet-rich plasma (PRP) tissue regeneration is applied intradermally by a needle for different indications, such as wound healing and scar revision. To prevent complaints such as pain, erythema, and ecchymosis by patients during this application, PRP was applied using Dermojet, a jet injector system with a spring-loaded system. In this study, after measuring the average platelet count in PRP preparations obtained from 18 volunteers, a 2.5 cc PRP shot into an empty tube was performed with Dermojet. The mean platelet count was measured in a homogenized tube. The same procedures were performed for platelet-poor plasma (PPP). The platelet loss rates for PRP and PPP were compared. In addition, the amount of PRP in each shot of the Dermojet was calculated. When PRP and PPP were applied using the Dermojet, platelet loss was 8.41% and 8.33%, respectively. The difference in the number of platelets formed in PRP and PPP when applied with Dermojet was not statistically significant. PRP application with needle-free injection systems, such as Dermojet, may be an alternative because of patient comfort and the negligible platelet loss compared with the PRP application with the standard needle injection.

Ultrasound-Guided Transforaminal Injections of Platelet-Rich Plasma Compared with Steroid in Lumbar Disc Herniation: A Prospective, Randomized, Controlled Study

Transforaminal steroid injection is extensively used as a treatment in cases of herniated disc, but it is associated with complications. In comparison, platelet-rich plasma (PRP) injection has been used in musculoskeletal disorders and could be another option. This study is aimed at comparing the efficacy and safety aspects between ultrasound-guided transforaminal injections of PRP and steroid in patients who suffer from radicular pain due to lumbar disc herniation. In a randomized controlled trial, ultrasound-guided transforaminal injections of either PRP (n = 61) or steroid (n = 63) were administered to a total of 124 patients who suffer from radicular pain due to lumbar disc herniation. Patients were assessed by the visual analogue scale (VAS), pressure pain thresholds (PPTs), Oswestry disability index (ODI), and the physical function (PF) and bodily pain (BP) domains of the 36-item short form health survey (SF-36) before operation and 1 week, 1 month, 3 months, 6 months, and 12 months after operation. The rate and latency of F-wave were obtained before operation and 12 months postoperation. There was no statistical difference in terms of age and sex between both groups. Statistically significant improvements from the patients' data before operation to data obtained 1-month postoperation were observed in VAS, PPTs, ODI, and PF and BP of SF-36 in both groups and kept for 1 year. F-wave rate and latency were improved significantly at 1-year postoperation in both groups. Intergroup differences during follow-ups over a period of 1 year were not found to be significant in all the above assessment between the PRP and steroid groups. No complications were reported. The results showed similar outcome for both transforaminal injections using PRP and steroid in the treatment of lumbar disc herniation, suggesting the possible application of PRP injection as a safer alternative. The trial was registered in the Chinese Clinical Trial Registry (ChiCTR-INR-17011825).

Platelet-Rich Plasma for Skin Graft Storage: An Experimental Study Using Rabbit Ears

BACKGROUND

Storage of surplus grafts for later use is one of the standard procedures used in plastic surgery. For the delayed use of skin grafts, various methods and media have been investigated for short-term storage. This study aimed to investigate the effect of platelet-rich plasma (PRP) skin graft storage on the survival of skin grafts obtained from rabbit ears.

MATERIALS AND METHODS

Twelve rabbits were used in this study. A total of 12 skin grafts measuring 1 × 1 cm were obtained from the inner surfaces of the rabbits' ears. The grafts were stored at +4°C in saline, Hartmann's, and PRP media. On days 3, 7, 10, and 14, the grafts were implanted into the ears in areas measuring 1 × 1 cm where the skin, cartilage, and perichondria were excised. After the implantation of the grafts, the survival rates were evaluated by measuring the graft areas on day 0, day 10, and day 30.

RESULTS

The graft survival rate decreased as the storage period increased in all 3 of the media. The decrease in survival rate was higher in the grafts that were stored in the Hartmann's media in comparison with the saline and PRP media, and the difference was statistically significant. The decrease in graft survival was similar between the storage in saline and PRP media; however, the differences were statistically insignificant.

CONCLUSIONS

Although in vitro criteria are important for evaluating graft survival, in vivo studies showing the graft take rate in the recipient area are required. When the in vivo criteria are evaluated, the use of PRP is not superior to the use of saline for graft storage. However, additional studies are required to evaluate the effects of PRP media on graft quality.

Effect of Intrauterine Infusion of Equine Fresh Platelets-Rich Plasma (PRP) or Lyophilized PRP (L-GFequina) on Ovarian Activity and Pregnancy Rate in Repeat Breeder Purebred Arabian Mares

Simple Summary

Persistent endometritis is one of the major causes of infertility in mares and results in endometrium degeneration, namely, endometrosis. Platelets-rich plasma (PRP) is an emerging therapeutic application in tissue regeneration because of its high concentration of growth factors with a high mitogenic and anti-inflammatory potential, but reduced preservation time. L-GF^equina is a freeze-dried, stabilized, platelet-rich plasma product (PP) that can be stored at 2 to 8 °C for several months. It can be easily used after reconstitution with sterile saline or water, eliminating the need for repeated blood product collection and special equipment. The intrauterine infusion of equine platelet-rich plasma or L-GF^equina can be used indistinctly in repeat breeder mares, shortening the estrous cycle, with no significant effect on the follicular diameter, as well as increasing pregnancy rate in Arabian purebred mares.

Abstract

This study was designed to examine the effect of the intrauterine infusion of platelet-rich plasma (PRP) or equine lyophilized growth factor (L-GF^equina) on the follicular growth, endometrial thickness, estrus cycle length, and pregnancy rate in purebred Arabian mares. A total of 73 purebred Arabian mares who experienced repeat breeding for three successive cycles were randomly divided into the following three groups: control group, without treatment; second Group (PRP group), in which mares were intrauterine infused with 20 mL of fresh PRP on the second day after the end of physic estrus phase; and the third group (L-GF^equina Group), consisting of mares that were intrauterine infused with 20 mL of reconstituted lyophilized horse platelets growth factors (L-GF^equina) on the second day after the estrus phase. The results showed no significant difference between control and treated groups in the diameter of the preovulatory follicles during the post treatment cycle. The endometrium thickness increased significantly in the L-GF^equina and PRP groups ahead of the non-treated group. Intrauterine L-GF^equina or PRP administration shortened the estrus cycle length. A higher pregnancy rate was recorded in the L-GF^equina and PRP treated mares. In conclusion, the intrauterine infusion of L-GF^equina or PRP increased the endometrial thickness and pregnancy rate and could be used to improve fertility in Arabian purebred mares who experienced from repeat breeding.

New design to remove leukocytes from platelet-rich plasma (PRP) based on cell dimension rather than density

Platelet-rich plasma (PRP) can stimulate the proliferation of stem cells and have a positive effect on tissue repair. Although many commercialized PRP preparation kits are already on the market, first-line clinical workers are still not satisfied with most of the PRP kits. The work of commercial PRP kits is based on the density of blood elements. However, the blood elements are very close in density which makes the separation challenging. Therefore, the mentioned commercialized kits are generally contaminated by leucocytes and erythrocyte. In this study, a home-designed PRP device was developed to use a separation membrane with adequate cut-off pore size of 5 μm, 3 μm and 2 μm for the groups of H5M, H3M, and H2M, respectively, to be placed in the middle of the centrifuge tube. The home-designed H2M showed a very promising results regardless of the final volume (1.82 ± 0.09 ml), platelet yield (8.39 ± 0.44%), Red Blood Cells (0%), White Blood Cells (0%), and Relative Concentration of Platelet Increment value (225.09%). Further, it showed a good result in cell viability and cytotoxicity and confirmed a good multilineage potentials. The concentration in PRP prepared by group H2M was relatively stable and far above average. All the fibrin fibers were linked together as bridging strands or strings and turned into an inter-connected porous structure for nutrients transportation and regenerative cell migration. We believe that the home-designed group H2M should have a great potential to develop into the final product to meet the requirements of first-line clinical workers.

•

The home-designed PRP device is a novel and effective method to remove leukocytes based on cell dimension.

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All the PRP products from the home-designed PRP devices have shown good the cell viability, and the multilineage potentials

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The H2M design could provide the stability of PRP compared to other groups and far above average.

[Modern ulcer surgery : Invasive treatment options using the example of therapy-resistant venous leg ulcers]

The socioeconomic significance of chronic venous leg ulcers is considerable due to the high number of patients, the costs of diagnosis and therapy, the deterioration in quality of life, and the loss of working capacity during the disease. This is further increased by a progressive course and an increased tendency to recurrence. Taking these facts into account, surgical treatment options are of particular importance, especially in otherwise therapy-refractory courses. For this purpose, an extensive spectrum of surgical and new, partly not yet finally evaluated, invasive techniques are now available. Venous surgery and endovenous closure techniques are suitable for eliminating primary or secondary varicosis as a causal therapy for venous leg ulcers. Shave therapy is the method of choice in the presence of dermatolipo(fascio)sclerosis. Current long-term results show good results with cure rates of 70-80%. In individual cases, surgical techniques involving fascia cruris (faciotomy, fasciotomy) can also be used. Recurrence ulcers can often be successfully treated by repeated shave therapy, optionally with simultaneous vacuum-assisted dressing techniques or by a fasciotomy. In addition, local invasive techniques such as autologous fat tissue transplantation or autologous platelet-rich plasma can be used to promote wound healing. Thus, both surgically invasive local therapy and advanced surgery of the causes of chronic venous leg ulcers play a key role in the overall therapy concept.

Comparison of Two Anticoagulants for Pain Associated with Platelet-Rich Plasma Injections

BACKGROUND AND AIM

Platelet-rich plasma (PRP) has long been used in skin rejuvenation and hair loss treatment. Some patients require multiple intradermal injections into the face and scalp, and the way in which these patients process and experience pain differs, depending on the patient. Minimizing pain and discomfort during nonsurgical procedures is essential for patient satisfaction. In our experience, the use of acid citrate dextrose-A (ACD-A) as an anticoagulant caused more patient discomfort than did sodium citrate (Na-citrate) among patients who underwent facial rejuvenation with PRP. The aim of the present study was to evaluate patient-related discomfort in PRP sessions using two different anticoagulants.

MATERIALS AND METHODS

This clinical trial included 10 patients who received facial PRP injections for facial rejuvenation and 10 patients who received PRP injections in their scalps for hair loss. On the application area, half the surface was treated with Na-citrate PRP injections, and the other half was treated with the same amount of ACD-A PRP injections. Neither the doctors who applied the treatment nor the patients were given information about which anticoagulant was used in each area. Immediately after the procedure, the patients were asked to score their pain on each side of the application area on a scale of 1-10 using a visual analog scale (VAS).

RESULTS

PRP injections using Na-citrate as an anticoagulant caused less discomfort on both the face and scalp as compared with that of ACD-A. The outcome was statistically significant.

CONCLUSION

Anticoagulants used in PRP preparation affected patients' pain perceptions during the injections. The sensation of pain with PRP prepared with Na-citrate as an anticoagulant was lower than that of PRP prepared with ACD-A. Further studies are required to evaluate the correlation between anticoagulants used for PRP preparation and pain feelings during injections.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Análise ultraestrutural do colágeno de feridas cutâneas de coelhos tratadas com plasma rico em plaquetas de equino

RESUMO O colágeno é sintetizado e segregado no espaço extracelular e organizados em fibrilas estriadas de acordo com o tipo de tecido. Utilizaram-se 24 coelhos brancos da raça Nova Zelândia, com idade de 12 meses e com 3,0kg de peso corporal, para avaliar a porcentagem de colágeno das feridas cutâneas tratadas com plasma rico em plaquetas de equino e pomada contendo gentamicina, sulfanilamida, sulfadiazina, ureia e vitamina A. Os animais foram separados em quatro grupos de igual número e submetidos à remoção de pele na região das linhas médias dorsal torácica (feridas tratadas) e lombar (feridas controle). As feridas torácicas foram tratadas com plasma rico em plaqueta de equino e pomada contendo gentamicina, sulfanilamida, sulfadiazina, ureia e vitamina A, e as do grupo controle somente com a pomada. Dos animais do grupo I, foi coletado tecido cutâneo, para a avaliação histológica e a ultraestrutural, com três dias de pós-operatório; dos animais do grupo II, com sete dias; do grupo III, com 14 dias; e do grupo IV, com 21 dias. Decorrido o período de avaliação de cada grupo, foi coletado fragmento de pele para avaliação da porcentagem de colágeno, bem como do diâmetro e da densidade da fibrila de colágeno por microscopia eletrônica de transmissão. O tratamento com PRP de equino associado à aplicação tópica da pomada mostrou-se eficaz na maturação das fibrilas colágenas e na antecipação do processo cicatricial.

Platelet-rich plasma and regenerative dentistry

Regenerative dentistry is an emerging field of medicine involving stem cell technology, tissue engineering and dental science. It exploits biological mechanisms to regenerate damaged oral tissues and restore their functions. Platelet‐rich plasma (PRP) is a biological product that is defined as the portion of plasma fraction of autologous blood with a platelet concentration above that of the original whole blood. A super‐mixture of key cytokines and growth factors is present in platelet granules. Thus, the application of PRP has gained unprecedented attention in regenerative medicine. The rationale underlies the utilization of PRP is that it acts as a biomaterial to deliver critical growth factors and cytokines from platelet granules to the targeted area, thus promoting regeneration in a variety of tissues. Based on enhanced understanding of cell signalling and growth factor biology, researchers have begun to use PRP treatment as a novel method to regenerate damaged tissues, including liver, bone, cartilage, tendon and dental pulp. To enable better understanding of the regenerative effects of PRP in dentistry, this review describes different methods of preparation and application of this biological product, and provides detailed explanations of the controversies and future prospects related to the use of PRP in dental regenerative medicine.

Skin graft storage in platelet rich plasma (PRP)

Storage of skin grafts for later use is one of the standard applications in surgery. It is the most preferred method to maintain at +4°C in refrigeration after wrapping the surplus grafts into sterile gauze pad moistened with saline. Although there are many studies on the storage of skin grafts, less is known about storing skin grafts with PRP. Twenty-five pieces of 1 × 1 cm² partial thickness skin graft were harvested from 12 patients during the reduction mammoplasty operation. Twenty-four grafts were divided into 4 groups, and each group consisted of 6 grafts, 1 graft was analyzed as Day 0. Grafts in Group 1, 2, and 3 were wrapped by sterile gauze pad moistened by either saline (Group 1) or Hartman (Group 2) or PRP (Group 3). Grafts were analyzed macroscopically and microscopically. There were no significant differences between media for the first 10 days. Decrease in viability was less in saline and PRP wrapped grafts at 20 day, viability decreased significantly in all environments after 20 days. Although there was no significant difference in saline or PRP storage, it was observed macroscopically that the grafts stored in the PRP appeared better.

The role of biologic agents in the management of common shoulder pathologies: current state and future directions

The field of orthopedic surgery has seen a rapid increase in the use of various biologic agents for the treatment of common musculoskeletal injuries. Most biologic agents attempt to harness or mimic naturally occurring growth factors, cytokines, and anti-inflammatory mediators to improve tissue healing and recovery. The most commonly used biologic agents are platelet-rich plasma and cells derived from bone marrow aspirate and adipose tissue. These agents have become increasingly popular despite a relative dearth of clinical data to support their use. Much confusion exists among patients and physicians in determining the role of these agents in treating common shoulder pathologies, such as glenohumeral osteoarthritis, rotator cuff tears, and tendinopathy. This article reviews the basic science and clinical evidence for the most commonly used biologic agents in the management of common shoulder pathology.

Treatment of symptomatic degenerative intervertebral discs with autologous platelet-rich plasma: follow-up at 5-9 years

Aim: This study assessed pain and function at 5-9 years postinjection in a subset of patients who received intradiscal platelet-rich plasma (PRP) injections for moderate-to-severe lumbar discogenic pain. Patients & methods: All patients received injections of intradiscal PRP in a previous randomized controlled trial. Data on pain, function, satisfaction, and need for surgery were collected at one time point of 5-9 years postinjection and compiled with existing data. Results: In comparison to baseline, there were statistically significant improvements in pain and function (p < 0.001). All improvements were clinically significant. Six patients had undergone surgery during the follow-up period. Conclusion: This subset of patients demonstrated statistically and clinically significant improvements in pain and function at 5-9 years postinjection.

Does Double Centrifugation Lead to Premature Platelet Aggregation and Decreased TGF-β1 Concentrations in Equine Platelet-Rich Plasma?

Blood-derived autologous products are frequently used in both human and equine medicine to treat musculoskeletal disorders. These products, especially the platelet-rich plasma (PRP), may contain high concentrations of growth factors (GFs), and thus improve healing in several tissues. Nevertheless, the procedures for preparation of PRP are currently non-standardized. Several protocols, which are based on distinct centrifugation patterns (rotation speed and time), result in PRPs with different characteristics, concerning platelet and GFs concentrations, as well as platelet activation. The aim of the present study was to compare two different protocols for PRP preparation: protocol (A) that is based on a single-centrifugation step; protocol (B), which included two sequential centrifugation steps (double-centrifugation). The results here reported show that the double-centrifugation protocol resulted in higher platelet concentration, while leukocytes were not concentrated by this procedure. Although platelet activation and aggregation were increased in this protocol in comparison to the single-centrifugation one, the TGF-β1 concentration was also higher. Pearson’s correlation coefficients gave a significant, positive correlation between the platelet counts and TGF-β1 concentration. In conclusion, although the double-centrifugation protocol caused premature platelet aggregation, it seems to be an effective method for preparation of PRP with high platelet and TGF-β1 concentrations.

Application of standardized platelet-rich plasma in elderly patients with complex wounds

In recent years, autologous platelet-rich plasma (PRP) derivatives have been used widely in the regeneration and repair of tissue, but a standard definition and preparation method for PRP are lacking. We developed a standardized method using platelet indices as quality-control indicators for PRP preparation. Twenty-one elderly patients (9 males, 12 females) with complex wounds were treated with standardized platelet-rich plasma (S-PRP). The platelet count in PRP after the second centrifugation was 1,069-1,436 × 10⁹ /L. We adjusted the platelet concentration in PRP after a second centrifugation to 1,000 × 10⁹ /L according to a formula using platelet-poor plasma (PPP). The standardized preparation method that we developed gave S-PRP with a relatively uniform platelet concentration. The wounds of 21 patients showed accelerated healing after S-PRP treatment, and there were no obvious side effects during treatment. These data suggest that our preparation method of S-PRP, using platelet indices as quality-control indicators with platelet count of 1,000 × 10⁹ /L could be used for the treatment of complex wounds in the elderly. The preparation method of S-PRP proposed in the present study may be a simple and effective method of PRP quality control.

Needleless electrospun and centrifugal spun poly-ε-caprolactone scaffolds as a carrier for platelets in tissue engineering applications: A comparative study with hMSCs

The biofunctionalization of scaffolds for tissue engineering is crucial to improve the results of regenerative therapies. This study compared the effect of platelet-functionalization of 2D electrospun and 3D centrifugal spun scaffolds on the osteogenic potential of hMSCs. Scaffolds prepared from poly-ε-caprolactone, using electrospinning and centrifugal spinning technology, were functionalized using five different concentrations of platelets. Cell proliferation, metabolic activity and osteogenic differentiation were tested using hMSCs cultured in differential and non-differential medium. The porous 3D structure of the centrifugal spun fibers resulted in higher cell proliferation. Furthermore, the functionalization of the scaffolds with platelets resulted in a dose-dependent increase in cell metabolic activity, proliferation and production of an osteogenic marker - alkaline phosphatase. The effect was further promoted by culture in an osteogenic differential medium. The increase in combination of both platelets and osteogenic media shows an improved osteoinduction by platelets in environments rich in inorganic phosphate and ascorbate. Nevertheless, the results of the study showed that the optimal concentration of platelets for induction of hMSC osteogenesis is in the range of 900-3000 × 10⁹ platelets/L. The study determines the potential of electrospun and centrifugal spun fibers with adhered platelets, for use in bone tissue engineering.

Platelet-rich plasma lyophilization enables growth factor preservation and functionality when compared with fresh platelet-rich plasma

Aims: To compare levels and activity of the growth factors between fresh and lyophilized platelet-rich plasma (PRP). Methods: Analysis of platelet concentration using fibroblast and human umbilical vein endothelial cell cultures were compared between fresh and lyophilized PRP obtained from peripheral blood. Results: After lyophilization, 54% of platelets were intact whereas the fresh showed no aggregation with agonists (levels under 20%). The concentration of growth factors (VEGF, EGF, TGF-β and PDGF) in both products were similar. Fresh and lyophilized PRPs induced proliferation in the fibroblasts at 24 h (0.303 vs 0.300, respectively). Conclusion: Lyophilized PRP appears to be an alternative to fresh PRP and the results evidenced the role of growth factors as a key element in the activity of this product.

Study of a Two-Step Centrifugation Protocol for Concentrating Cells and Growth Factors in Bovine Platelet-Rich Plasma

There is a lack of information about the methods used for bovine platelet-rich plasma (PRP)/platelet-rich gel (PRG) procurement, including information on platelet (PLT), white blood cell (WBC) in PRP, and growth factor release from PRG supernatants. The aims of this study were to compare and to correlate the PLT, WBC, transforming growth factor beta-1 (TGF-β₁), and platelet-derived growth factor BB (PDGF-BB) concentrations in bovine whole blood, plasma, and four PRP layers and their respective PRG supernatants: A and B (obtained by a single centrifugation tube method at 720g/5 min) and C and D (obtained by a double centrifugation tube method, by using two centrifugation episodes at 720g/5 min). PLT and WBC counts were significantly higher in PRP-C, followed by whole blood, PRP-A, PRP-B, and PRP-D. TGF-β₁ concentrations were significantly higher in PRG-B supernatants and its correspondent PRP-B lysate when compared to the other PRG supernatants and plasma. Supernatants from PRG-A, PRG-B, and PRG-D had equivalent TGF-β₁ concentrations. PDGF-BB concentrations were not statistically different between the hemoderivatives. Significant Pearson correlations were noted between PLT counts and WBC counts (0.8) and between PLT counts and PLT distribution width (0.6). Further studies should be performed to assess the potential clinical applications of these PRPs.

The use of platelet-rich plasma to treat chronic tendinopathies: A technical analysis

Platelet-rich plasma (PRP) is blood plasma with a high concentration of autologous platelets which constitute an immense reservoir of growth factors. The clinical use of PRP is widespread in various medical applications. Although highly popular with athletes, the use of PRP for the treatment of tendinopathies remains scientifically controversial, particularly due to the diversity of products that go by the name of "PRP." To optimize its use, it is important to look at the various stages of obtaining PRP. In this literature review, we take a closer look at eight parameters which may influence the quality of PRP: 1) anticoagulants used to preserve the best platelet function, 2) the speed of centrifugation used to extract the platelets, 3) the platelet concentrations obtained, 4) the impact of the concentration of red and while blood cells on PRP actions, 5) platelet activators encouraging platelet degranulation and, hence, the release of growth factors, and 6) the use or nonuse of local anesthetics when carrying out infiltration. In addition to these parameters, it may be interesting to analyze other variables such as 7) the use of ultrasound guidance during the injection with a view to determining the influence they have on potential recovery.

Controlled delivery of platelet-derived proteins enhances porcine wound healing

Platelet-rich plasma (PRP) is widely used for many clinical indications including wound healing due to the high concentrations of growth factors. However, the short half-life of these therapeutic proteins requires multiple large doses, and their efficacy is highly debated among clinicians. Here we report a method of protecting these proteins and releasing them in a controlled manner via a heparin-based coacervate delivery vehicle to improve wound healing in a porcine model. Platelet-derived proteins incorporated into the coacervate were protected and slowly released over 3weeks in vitro. In a porcine model, PRP coacervate significantly accelerated the healing response over 10days, in part by increasing the rate of wound reepithelialization by 35% compared to control. Additionally, PRP coacervate doubled the rate of wound contraction compared to all other treatments, including that of free PRP proteins. Wounds treated with PRP coacervate exhibited increased collagen alignment and an advanced state of vascularity compared to control treatments. These results suggest that this preparation of PRP accelerates healing of cutaneous wounds only as a controlled release formulation. The coacervate delivery vehicle is a simple and effective tool to improve the therapeutic efficacy of platelet-derived proteins for wound healing.

Growth Factor Variation in Two Types of Autologous Platelet Biomaterials: PRP Versus PRF

Autologous platelet biomaterials represent a key source of cytokines and growth factors extensively used for clinical and surgical applications involving tissue regeneration; wound healing and tissue repair. In this communication we discuss the growth factors released by activated platelet rich plasma (PRP) and platelet rich fibrin (PRF) releasate. Our study highlights that significantly higher growth factors (TGF-ß1) are released by activated PRP as compared to releasate of PRF. The various growth factors released by both platelet products are significantly higher than the baseline concentration in the whole blood and have different bio-mechanism hence should be individualized as per the clinical indication.